Our objective is to elucidate the mechanisms that regulate gene expression in mammalian cells, particularly mechanisms that regulate alpha-fetoprotein (AFP) gene transcription during ontogenesis and hepatocarcinogenesis. We determined that differentiation and hepatocarcinogenesis involved a change in the transcriptional activity of the AFP gene. We plan to further examine the relationship of chromatin structure and DNA methylation to AFP gene activity. We identified hepatoma-associated nonhistone proteins in AFP-producing hepatomas. We will continue to identify nuclear proteins that affect AFP gene hepatomas. We will develop an in vitro transcription system to examine how nuclear proteins, hormone receptors and carcinogens affect AFP gene transcription.